Itchy sex: On being allergic to your lover

Q.Of the many pitfalls to romance, is it possible to be allergic to your lover's body? How about your own? ­Ben Adryl

A. There are rare cases of women who become allergic to a protein in seminal fluid, with symptoms ranging from genital inflammation and itchiness to anaphylactic shock involving hives and difficulty breathing after intercourse, says Capt. Jay R. Montgomery, MC, USN, of Walter Reed Army Medical Center.

Probably this is a type of hypersensitivity reaction like an allergy to certain foods or bee sting. Condom use is a preventative. Treatments may range from vaginal creams to immunotherapy, or for fertility, artificial insemination may be necessary using sperm devoid of seminal plasma.

Interestingly, men too can be allergic to their own sperm, says University of California-San Francisco urologist Paul Turek. The basis for this is that the testicles are an "immunologic sanctuary," safe from the body's immune system.

This is necessary because sperm are not created in the early years when the man's immune system is developing, so later at puberty, sperm are regarded as alien invaders.

Normally, this is under good control, says Turek, unless perhaps prior vasectomy and reversal expose the sperm to the rest of the body, threatening fertility.

Rounding out the reproductive weirdness, reports the University of Health Sciences, Chicago Medical School, is that some women develop an allergic response to their own fetus, risking miscarriage or that the pregnancy won't take.

It's as if our reproductive machinery sits within us but is not always quite of us– in uneasy biological truce.

Q.In an emergency, would you be more likely to get help from a bystander who's sober or who's drunk? G. Samaritan

A. Bet on the drunk. This is especially true where a number of bystanders are present, all strangers. So strong is this that in one study where researchers leaked smoke into a waiting room, 62 percent of the groups tested did nothing, "even when the smoke became so thick that it was hard to see," say Robert Baron et al. in Social Psychology.

But when bystanders were alone in the waiting room, 75 percent went for help, usually within two minutes.

One reason groups don't respond is that people are afraid they're misinterpreting the situation, and don't want to look dumb or silly. Drunks don't think this way, though. Said one researcher, "Now, you might not want the help of a drunk... I don't know about the quality of the help you'd get, but they're more likely to do it."

Q.Why is jet lag worse for eastbound flights? Or answer this: If you holed yourself up in a cave, without clocks or daylight cues, would your "days" tend to lengthen or shrink? ­S. Thomas

A. Mysteriously, young adults in cave experiments typically adopt a 25-hour day, says David G. Myers in Psychology. This seems to be what the human body "clock" is set for. So an east to west flier, who gains hours in the day, will experience less circadian rhythm disruption than a west to east traveler, whose body clock tends to run on into the wee hours of the new time zone.

For the same reason, most of us have little trouble staying up later than usual, and tend to do so on weekends, making for a biorhythm crash come Monday morning.

Q.It's been used to trace ancestries, solve crimes, assess organ donor-recipient compatibility, optimize mate selection for endangered species, settle patent cases involving genetically engineered organisms, identify the origin of hides or tusks in suspected poachings, and even to answer historical riddles such as whatever happened to the son of Marie-Antoinette following her beheading. What is this revolutionary procedure, much in the news these days? –Duh

A. Right, DNA analysis, useful whenever it might be important to trace the lineage of humans, animals or plants, say Mahlon Hoagland et al. in Exploring the Way Life Works: The Science of Biology. In 1999, scientists DNA-tested the preserved heart of the presumed Dauphin Louis XVII of France, son of Louis XVI and Marie-Antoinette, both guillotined in 1793 at the height of the French Revolution. The child reportedly died in prison, but rumors swirled of his escape, and many people claimed to be him or one of his descendants.

The child's heart had been removed at autopsy, ending up at the royal crypt outside Paris. DNA from Marie-Antoinette's hair follicle cells and from two of her sisters were compared with DNA from the heart and from two of the sisters' living descendants. "The comparison confirmed that the heart was indeed that of the unlucky 10-year-old."